Tributes pour in for King of Pop
Music producer Quincy Jones told MSNBC: "I am absolutely devastated at this tragic and unexpected news."
He said Jackson "had it all - talent, grace, professionalism and dedication".
He added: "I've lost my little brother today, and part of my soul has gone with him."
Demi Moore paid tribute on Twitter, writing: "I am greatly saddened for the loss of both Farrah Fawcett and Michael Jackson. Especially for their children!"
Her husband, Ashton Kutcher, also posted: "RIP. Sending love and light to family and friend but especially his kids."
He added: "Plea to the press to respect his wishes of maintaining the anonymity of his children. I plea to the public to refuse to consume media that does not respect the anonymity of Michaels children."
Foreign Secretary David Miliband wrote on Twitter: "Never has one soared so high and yet dived so low. RIP Michael."
Rev Al Sharpton, a leading US civil rights campaigner and friend of Jackson, told Sky News: "As a friend of Michael's for the past 35 years, I call on people from around the world to pray for him and his family."
Singer Cher said on the BBC website: "I'm having a million different reactions I didn't expect I would feel.
"He was a great singer - God gives you certain gifts and this child was just an extraordinary child touched by this ability. He could sing like nobody else and he was able to connect with people."
Fellow singer Celine Dion added: "I am shocked. I am overwhelmed by this tragedy. Michael Jackson has been an idol for me all my life.
"He was not only a talented person but he was unique - a genius. It's such a loss. It feels like when Kennedy died, when Elvis died. My sympathy goes to the family. It's a big loss and it's not even sinking in right now."